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jack_mp3.py
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jack_mp3.py
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### jack_mp3 - mp3 layer stuff for
### jack - extract audio from a CD and MP3ify it using 3rd party software
### Copyright (C) 1999-2001 Arne Zellentin <zarne@users.sf.net>
### Transformed from mp3info (c) Thorvald Natvig
### This program is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
### This program is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
### GNU General Public License for more details.
### You should have received a copy of the GNU General Public License
### along with this program; if not, write to the Free Software
### Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
DEBUG = 0
import string, types
from os import stat
from stat import ST_SIZE
from StringIO import StringIO
global warnings
global F, f, xing, id3v2, start_offset
# constants
mode_names = ["stereo", "j-stereo", "dual-ch", "single-ch", "multi-ch"]
layer_names = ["I", "II", "III"]
version_names = ["MPEG-1", "MPEG-2 LSF", "MPEG-2.5"]
version_nums = ["1", "2", "2.5"]
bitrates = \
[[[ 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448],\
[0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384],\
[0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320]],\
[[0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256],\
[0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160],\
[0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160]],\
[[0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256],\
[0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160],\
[0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160]]]
s_freq = \
[[44100, 48000, 32000, 0],\
[22050, 24000, 16000, 0],\
[11025, 8000, 8000, 0]]
bpf_fact = [0, 12000, 144000, 144000]
# Xing stuff
FRAMES_FLAG = 0x0001
BYTES_FLAG = 0x0002
TOC_FLAG = 0x0004
VBR_SCALE_FLAG= 0x0008
def get_l4 (s):
return reduce(lambda a,b: ((a<<8) + b), map(long, map(ord, s)))
def decode_xing():
global F, f, xing
# defaults:
frames = bytes = scale = toc = None
where = f.tell()
try:
if 1:
if DEBUG: print "Xing at", where
# 32-bit fields; "Xing", flags, frames, bytes, 100 toc
flags = get_l4(f.read(4))
if flags & FRAMES_FLAG:
frames = get_l4(f.read(4))
if flags & BYTES_FLAG:
bytes = get_l4(f.read(4))
if flags & TOC_FLAG:
toc = map(lambda x: ord(x), f.read(100))
for j in range(len(toc)):
toc[j] = int(toc[j] / 256.0 * bytes)
if flags & VBR_SCALE_FLAG:
scale = get_l4(f.read(4))
if DEBUG>2:
print "Xing: frames=%i" % frames
print "Xing: bytes=%i" % bytes
print "Xing: toc=", toc
print "Xing: scale=%i" % scale
xing = {}
if frames: xing['x_frames'] = frames
if bytes: xing['x_bytes'] = bytes
if toc: xing['x_toc'] = toc
if scale: xing['x_scale'] = scale
xing['x_header_at'] = where - 4
else:
return None
except:
if DEBUG:
import traceback
traceback.print_exc()
f.seek(where + 1)
return None
def find_xing(framelen):
"read (and skip) the Xing header if present"
where = f.tell()
x = f.read(framelen)
pos = string.find(x, "Xing")
if pos >= 0:
f.seek(where + pos + 4)
decode_xing()
f.seek(where + framelen)
else:
f.seek(where)
def reread_f(size):
global F, f
pos = f.tell()
f.seek(F.offset)
if DEBUG: print "reread_f: now at", f.tell()
F_offset = F.offset
F_file = F.file
F = StringIO(f.read(F.len + size + 10))
F.file = F_file
F.offset = F_offset
f.seek(pos)
def handle_id3v2(version, flags, data):
global id3v2
if DEBUG: print "ID3:", `version`, `flags`, len(data)
id3v2 = {}
id3v2['version'] = tuple(version)
def read_id3v2():
#$49 44 33 yy yy xx zz zz zz zz ; yy < $FF; zz < $80
# I D 3 yy yy xx zz zz zz zz
# 0 1 2 3 4 5 6 7 8 9
global F, f
where = f.tell()
header = f.read(10)
if header[:3] != "ID3":
if DEBUG: print "no header?", where, `header`
f.seek(where)
return None
header = list(header)
for i in range(3,10):
header[i] = ord(header[i])
if not (header[3] < 0xff) or not (header[4] < 0xff):
f.seek(where)
return None
if not (header[6] < 0x80) or not (header[7] < 0x80):
f.seek(where)
return None
if not (header[8] < 0x80) or not (header[9] < 0x80):
f.seek(where)
return None
size = header[6:]
size = list(size)
value = 0
for i in size:
value = value << 7
value = value | i
size = value
reread_f(size)
flags = header[5]
version = header[3:5]
return handle_id3v2(version, flags, f.read(size))
def decode_header(buffer):
"get mp3 info. Transformed from mp3info (c) Thorvald Natvig"
try:
switch = (ord(buffer[1]) >> 3 & 0x3)
if switch == 3:
version = 0
elif switch == 2:
version = 1
elif switch == 0:
version = 2
else:
return None
bitrate_index = (ord(buffer[2]) >> 4) & 0x0F
sampling_frequency = (ord(buffer[2]) >> 2) & 0x3
mode = (ord(buffer[3]) >> 6) & 0x3
x = {}
x['error_protection'] = not (ord(buffer[1]) & 0x1)
x['padding'] = (ord(buffer[2]) >> 1) & 0x01
x['extension'] = ord(buffer[2]) & 0x01
x['mode_ext'] = (ord(buffer[3]) >> 4) & 0x03
x['copyright'] = (ord(buffer[3]) >> 3) & 0x01
x['original'] = (ord(buffer[3]) >> 2) & 0x1
x['emphasis'] = (ord(buffer[3])) & 0x3
x['mode_name'] = mode_names[mode]
x['lay'] = 4 - ((ord(buffer[1]) >> 1) & 0x3)
x['layer_name'] = layer_names[x['lay'] - 1]
x['version_name'] = version_names[version]
x['version_num'] = version_nums[version]
x['bitrate'] = bitrates[version][x['lay'] - 1][bitrate_index]
if not x['bitrate']: raise IllegalError_may_be_free_format
x['sfreq'] = s_freq[version][sampling_frequency]
if not x['sfreq']: raise IllegalError_illegal_sfreq
except:
if DEBUG:
import traceback
traceback.print_exc()
print "Illegal header, so far:", x
x = None
return x
def extend_frameinfo(x):
if x['version_num'] == "1":
x['samples_per_frame'] = 1152
elif x['version_num'] == "2":
x['samples_per_frame'] = 576
else:
print "What is the spf for %s?" % x['version_name'], "(%s)" % x['version_num']
# calculate BPF
x['bpf'] = (x['bitrate'] * bpf_fact[x['lay']]) / x['sfreq']
x['framesize'] = (x['bitrate'] * bpf_fact[x['lay']]) / x['sfreq'] + x['padding']
#stereo = (mode == MPG_MD_MONO) ? 1 : 2;
return x
def syncronize(what = 1):
global F, f
index = f.tell()
x = {}
#search intelligently (i.e. fast) for any header
fields = ["\377", "I", "X", "R"][:what]
if not warnings: fields.remove("R")
#while index < len(f.buf) - 4:
while index < F.len - 4 + start_offset:
#print index
if F.buf[index - start_offset] in fields:
if F.buf[index - start_offset + 1] >= "\340":
# a valid header must start with 11 set bits
f.seek(index)
x = decode_header(f.read(4))
if x:
where = f.tell() - 4
x['header_at'] = where
x = extend_frameinfo(x)
next_header = where + x['framesize']
if DEBUG: print "MPEG header found at %i, expect next header at %i." % (x['header_at'], next_header)
f.seek(next_header)
buf = f.read(4)
y = None
if buf[:2] >= "\377\340":
y = decode_header(buf)
if y:
# two headers, that's certain enough.
f.seek(x['header_at'])
break
else:
if DEBUG: print "but no valid header follows at %i." % next_header
f.seek(where)
index = where
x = None
elif F.buf[index - start_offset:index - start_offset + 3] == "ID3":
if not id3v2:
f.seek(index)
read_id3v2()
if id3v2:
if DEBUG: print "ID3v2 found, now at %i" % f.tell(), id3v2
index = f.tell()
fields.remove("I")
continue
else:
f.seek(index)
elif F.buf[index - start_offset:index - start_offset + 4] == "Xing":
f.seek(index + 4)
decode_xing()
if xing:
if DEBUG: print "Xing header found without frame sync."
index = f.tell()
fields.remove("X")
continue
else:
f.seek(index + 4)
elif F.buf[index - start_offset:index - start_offset + 4] == "RIFF":
if warnings: print "skipping RIFF header at %i..." % F.tell()
fields.remove("R")
index = index + 1
return x
def mp3format(file, warn = 1, max_skip = 100000, offset = 0):
global F, f, xing, id3v2, warnings, start_offset
warnings = warn
start_offset = offset
f = xing = id3v2 = None
if DEBUG: print "examining", file, "warnings=%i" % warnings, "offset=%i" % start_offset, "max_skip=%i" % max_skip
# XXX we're using StringIO because it's faster - transitionally.
if type(file) == types.StringType:
f = open(file, "r")
elif hasattr(file, 'seek'):
f = file
else:
print "unknown object:", file
return None
f.seek(start_offset)
search_in = f.read(max_skip)
F = StringIO(search_in)
F.file = file
f.seek(start_offset)
F.offset = start_offset
x = syncronize(what = 4)
if not x:
if warnings: print "Warning: no MP3 header found in the first", F.tell(), "bytes of file\n : \"" + file + "\"."
return {}
# we're quite sure we have a valid header now
if warnings > 1:
print "Warning: MP3 header found at offset", f.tell() - 4
# fill in convenience stuff
x = extend_frameinfo(x)
# the xing header is normally embedded in the first valid frame
# but sometimes it appears earlier, I don't know why. Use the 1st.
if not xing:
find_xing(x['framesize'])
if xing:
x.update(xing)
if x.has_key('x_frames'):
x['length_in_samples'] = x['x_frames'] * x['samples_per_frame']
x['length'] = float(x['length_in_samples']) / x['sfreq']
# should use the real file size instead of x_bytes.
if x.has_key("x_bytes"):
x['bitrate'] = int((x['x_bytes'] * 8.0 / x['length']) / 100 + 0.5)
x['bitrate'] = x['bitrate'] / 10.0
else:
print "strange xing=" + `xing`
else:
x['length'] = stat(file)[ST_SIZE] * 8.0 / (x['bitrate'] * 1000)
if id3v2:
x['id3v2'] = id3v2
if DEBUG > 1: print x
return x
class MP3:
def __init__(self, file, name=None):
self.file = None
self.name = name
if type(file) == types.StringType:
self.file = open(file, "rb")
self.name = file
elif hasattr(file, 'seek'):
self.file = file
else:
print "unknown object:", file
return None